Hello there!
For some time now I try to figure out how these guys were able to add "Sign online here" button which is "install App" button on their fan-page tab:
http://www.facebook.com/GuinnessIreland?v=app_165491161181
I've read around the web and couldn't come up with any solid solution. The FBML and FBJS documentation left me with nothing.
So please, if anyone can help me with this.
NOTE: To make multiple tests on the Ajax request that are sent, do not accept the App install. It behaves differently after that.